1. Field of the Invention
This application relates to the field of electric test devices and more particularly to the field of electric test devices having an illumination unit.
2. Description of Related Art
Test devices for measuring electrical voltages are known in the art. Such devices are frequently pen-shaped, with an electrical circuit arranged inside a handle portion which can be held by an operator. A pin which is connected to the electrical circuit, extends away from the front end of the handle portion and can be brought into electrical contact with a wire to be tested. Examples of such voltage testers are described, for example, in the U.S. Pat. Nos. 5,293,113 and 5,448,162 commonly assigned to the Applicant.
Test devices are frequently used under poor viewing conditions, in particular when the wires to be tested are difficult to access. In particular under unfavorable lighting conditions, the operator may have difficulty finding the correct wire. To illuminate the area of interest, the operator may have to use a separate flashlight or a lamp connected with an extension cord which may be difficult to implement.
It is therefore desirable to provide a test device for electrical voltages which takes up little space and which does not require an external light source even under difficult lighting conditions.
According to an aspect of the invention, a test device for electrical voltages is integrated with an illumination device in a common housing which can be used both as a voltage sensor and as a flashlight. The test device further includes a processing circuit for processing the measured voltage signals, display elements for displaying these signals, and a galvanic element for supplying power to the device. With these features, the test device is simple, has a small footprint and can be easily carried. Moreover, the test device is adapted for testing electrical voltages under difficult lighting conditions and can also be used as a stand-alone flashlight.
The housing is preferably elongated and shaped like a pen. The housing may also be provided with a clip so that the test device can be easily carried, much like a writing utensil. With the elongated pen-shaped arrangement, the voltage sensor can be advantageously arranged in one end of the housing, while an illumination device is arranged in the other end of the housing, so that the sensor and the illumination device can be used independently. The elongated housing may also be adapted to receive cylindrical galvanic elements, for example, a primary galvanic cell or a rechargeable battery.
The processing circuit may be arranged on a narrow elongated printed circuit board to be received in the elongated pen-shaped housing. The elongated printed circuit board is preferably oriented parallel to the galvanic element(s) and may be inserted into a guide rail or channel provided in the housing.
The voltage sensor may be implemented as an electrically conducting pin or strip operating as an antenna, wherein the pin or strip terminates in a extended tip of the housing. With this arrangement, a voltage can be measured contactless with high sensitivity.
According to another advantageous embodiment, a magnetic sensor can be integrated into the housing. The magnetic sensor is preferably a Reed contact. A test device equipped with such a magnetic sensor can readily detect magnetic fields, thereby obviating the need for a separate test device.
The housing may be provided with a removable end cap to facilitate replacement of the galvanic element(s) and/or device maintenance and repair. The end cap may include a lamp of the illumination device. A plug connection between the end cap and the housing is provided with electrical contacts, thereby providing a reliable mechanical seat of the end cap on the housing as well as an electrically conducting connection between the lamp and a corresponding switch located in the housing of the test device.
The switch for switching the lamp power on and off can be implemented in several ways. For example, the switch may be a slide switch. The switch may also be a rotary switch and advantageously actuated by rotating the end cap relative to the housing. For example, the end cap may be rotated clockwise to turn the lamp on and rotated counter-clockwise to turn the lamp off, or vice versa. The switch for activating the lamp function may also be a simple push-button switch or toggle switch disposed on the housing.
According to another advantageous embodiment, the switch can be in the form of a clip disposed on the housing. The test device can thereby be attached with the clip to, for example, a shirt pocket and the like. The clip may also operate as a switch.
Display elements for displaying the voltage are preferably light emitting diodes (LEDs), wherein the housing is transparent to light at least in the region of the LED""s. The LED""s and the light-transmissive region of the housing, respectively, can have different colors to make it easier to differentiate between displayed voltages and displayed magnetic fields.
In addition to the visual display, the housing may incorporate an acoustic indicator, for example, a buzzer.
Further features and advantages of the present invention will be apparent from the following description of preferred embodiments and from the claims.